Electric hot-plate or heat unit.



.IVI. E. LOUTH 1&1. JACKSON.

ELECTRIC HOT PLATE 0R HEAT UNIT.

APPLICATION FILED JULY 28,19I5.

2 SHEETS-SHEET I.

Patented Sept. 4, 1917.

'III'...

desse Jac/rsa By WI ATTORNEYS TEI- lvl. E. LOUTH L J. JACKSON.

ELECTRIC HOT PLATE 0R HEAT UNIT.

APPLICATION FILED JULY 28, I9I5.

/lvI/E/vms Maar/ce f. .Loaf/1 dass@ Jackson Kw2 .A UUR/V515 UNITED STATES MAURICE E. LOUTH .AND JESSE JACKSON, 0F KOK-OLMO, INDIANA, ASSIGNORS TO THE GLOBE STOVE & RANGE COMPANY, OF KOKOMO, INDIANA.

ELECTRIC HCT-PLATE OR HEAT UNIT.

Specification of Letters Patent.

Patented Sept. 4, 191'?.

To all whom t may concern:

Be it known that we, MAURICE E. LOUTH and JESSE JACKSON, citizens of the United States, residing at Kokomo, Indiana, have invented certain new and useful Improvements in Electric Hot-Plates or Heat Units, of which the following is a specification.

This inventionrelates to improvements 1n electric hot plates or heat units.

The objects of the invention are:

First, to provide an effective electric heating unit or hot plate of large capacity.

Second, to provide means of utilizing the maximum of the heat developed.

Third, to provide a structure of single or multiple heat hot plate or unit adapted to compensate for the expansion with the strongest heat element disposed at the center.

Fourth, to provide an improved insulating support and guard means for the heating coil.

Fifth, to provide a heating unit with a metallic top plate adapted to compensate for the expansion due to heat.

Sixth, to provide an improved construction whereby the electrical connecten is made or established by merely placing the unit in position.

Further objects, and objects relating to details and economies of construction and operation will definitely appear from the detailed description to follow.

We accomplish the objects of our invention by the devices and means described in the following specification. The invention is clearly defined and pointed out in the claims..

A structure which is a preferred embodiment of our invention is fully illustrated in the' accompanying drawing, in which:

Figure I is a plan view of our improved hot plate or heat unit detached or removed from its support.v

Fig. II is a detail sectional elevation view on a line corresponding to line 2 2 of Fig.

I, showing the hot plate in position on the support. l

Fig. III is an enlarged detail sectional view taken on the line corresponding to the irregular line 3-3 of Fig. I, showing the binding posts and slotted pin connections 1n lposition on the plate and disposed in suitable sockets in the supporting base.

Fig. IV is a detail plan view of the insulator disk, showing the disposition of the heating coils therein, the top guard plate being removed.

Fig. V is a detail perspective view of the structure modified and adapted especially to use a simple hot plate on a hollow base.

Fig. VI is an enlarged detail sectional view onl line 6 6 of Fig. V, showing details of the arrangement and construction.

In the drawing all of the sectional views are taken looking in the direction of the little arrows at the ends of the section lines, and similar numerals of reference refer to similar parts throughout the several views.

Considering the numbered parts' of the drawing, the base 1 may be of any suitable construction. In the preferred construction we show the same hollow and filled with a suitable insulating lilling 2, such as asbestos or mineral wool or 'the like. The base may be hollow, but when the hot plate is incorporated in a range or made use of in a lireless cooker it may be put in a recess in the top of the outer shell.

The insulating disk 3 which carries the heating coils is disposed in a recess B, where it is protected andthe heat therefrom is in a measure confined, although the plate being of insulating material very little heat descends below the bottom thereof. A plate 4, of disk form and of larger diameter than the insulating plate is secured thereto by bolts 5, 5 disposed through the said metallic top plate and into slots 6 in the insulating disk. The insulator disk is preferably made of porcelain. The nuts of the bolts 5 are not drawn tight, as it is necessary to permit free expansion and contraction in order to prevent breaking of the parts.

A groove 7 is formed in the top of the insulating plate 3 in which is disposed the heating coil 8. This outer coil 8 is connected to the binding posts 9 and 10 and is formed just within the periphery of the insulator disk 8. A second coil 11 is disposed in the grooves 12, 13, which are looped back and forth in substantially parallel relation at the center in elongated loops, and provided with a portion extending substantially parallel to the outer peripheral groovei. The terminal 15- is connected to the binding post 14 and the terminal 16 connected to post 9. It willthus be seen that the central portion of the heating coil is made up of portions disposed in substantially parallel relation. The outer coil is preferably of the greater resistance.

rlhe coils are retained in position by little cotter .pins l? (see Fig. ll) extending down through perforations in the bottom of the grooves, these being distributed at such quent intervals as'to effectively retain the coils dat down in the bottom, the coils be- `ing preferably attened as shown, or the feo coils can be cemented in place.

The top plate 3 has a comparatively broad unperforated peripheral flange which is cast with slots 18, 18 on opposite sides thereof and toward the sides of 'the elongated grooves in the plate at vthe center L series of segmental slots i9, 20, 2l 22 extend substantially around the plate, ei;- cept for the connecting support 23 opposite the ends of the groove the center and the connections 2e and 25 at each side in proximity to the open slots i8 and diametrically and symmetrically opposite therefi in, 'and the central connection part 26 in the region of the binding posts. The part 23 extends well in at`27 and the part 26 eX- tends well in at the opposite side, forming sort of end to the central grid. Segments of metal are disposed between the slots 28, 29 toward the outside and at 30, 81 just within the same, and 32, 33, 34, 35 and 36V in parallel relation at center forming elongated slots corresponding to the grooves in the insulator plate beneath. 'On the opposite sides of each of the slots as formed extend little guard lingers 37 which prevent any articles, such as a spoon, a knife, or a fork from being dropped down into contact with the resistance heating coils and thus grounding the same.

Because of the elongated arramgrement of the coils and slots at the center and the portions guarded from direct cont-act with the heating units, except where the coils deliver least heat obecause they are somewhat expanded in turning the corners, the

expansion of the unit is lengthwise of these parts, and consequently the guard does not become materially displaced fromover the grooves of the insulator disk containing` the heating coil below. Because of the disposition and arrangement in this direction, the opposite sides of the disk are moved in relation to each other and close up the slots 18 on the opposite sides, thus making the outer ring continuous, and serving as an effective guard for the coils within in case of the accidental spilling of the contents of any dish. At the sane time, owing to this expanding in'this way there is no appreciable tendency for the center of the hot plate to bulgeup and a perfectly level polished surface is secured for the supporting of a Hat lbottom dish or kettle which is the only kind that is available for use in this behalf. The broad fiat flange at the periph ery serves to retain the heat and because of its broad contact with the dish or object being heated above it conducts its heat and delivers it where required without undue dissipation by radiation.

The binding posts for the coils extend down through the insulation and terminate in split pins or rings 39 which are inserted in suitable sockets 4:0. The sockets are provided with suitable electrical connecticns il which are controlled by one or more suitable switches for the proper delivery of the current to the resistance coils constituting-the hea er.

In the preferred construction, this heater will be placed in the top of a freless cooker or electric range, which is made as indicated in r rlhe structure is also very well apted to very simple kind of hot plate structure which is preferably supported on a hollow casing` e2, having a suitable perforated base el and a suitable top e5, provided with a suitable opening receive the top plate and support lbv the periphery of the plate il, which constitutes flange for that purpose in either case. The

heat unit can be let into any suitable table top or into the top of any work bench, or it may be otherwise effectively supported. lt is, however, desirable and preferable that it be supported by a surrounding plate with a suitable space to receive it. YWhile it is desirable to have an inclosed pocket or chamber beneath the insulator plate for sanitary reasons, as it greatly facilitates cleaning the parts and somewhat increases the effectiveness of the heater, yet that is not necessary and very satisfactory results are obtained without it.

We desire to claim the structure specifically as we have it shown and also desire to claim the broad features' as pointed out in the appended claims.

Having thus described our invention what we claim as new and desire to secure by Let ters Patent is: e

l. ln an electric heat unit, the combination of an insulator plate with suitable l grooves in the face thereof, heating coils disposed in said grooves, a metallic shield plate disposed over said insulator plate with a broad rim extending into a flange beyond said insulator plate, with radial slots therein and slots corresponding to the grooves in said plate,bolts through the said shieldplate and insulator plate disposed in slots in said insulator plateto permit expansion and contraction, means for retaining the coils in said grooves, terminal pins projecting downwardly from the under surface of said insulatorplate and connected to the terminals of said heating coils, a base with an opening in its top to receive said insulator plate and engage the flange, and sockets in the base portion to receive said terminal pins, as specified.

2. In an electric heat unit, the combination of an insulator plate with suitable grooves in the face thereof for receiving the heating coils, one of which grooves is toward the periphery and the other of which is within the outer groove with its central portion looped back and forth somewhat in the form of a grid, a plurality of heating coils disposed and retained within the said grooves with suitable terminal connections whereby the same can be thrown in singly or together, the outer coil having the greater resistance, a metallic shield plate disposed over the said insulator plate with a broad rim extending into a flange beyond said insulator plate and with radial slots on opposite s ides of said grid part, peripheral segment-al slots corresponding to the peripheral grooves in the plate beneath and central bars with connections to the peripheral flange at intervals, whereby said bars form slots segmental in form and form a grid-like structure corresponding to the grooves at the center of the insulator plate, with connecting portions toward the ends of said grooves and connecting portions from the sides of the outer bars to the flange rim toward each side in proximity to the radial slots therein.

3. In an electric` heating unit, the combination of an insulator plate with a suitable groove in the face thereof, a heating coil disposed in said groove, and Ya metallic shield plate disposed over said insulator plate with slots therein corresponding to the said groove and alternately projecting fingers on opposite sides of said slots to shield the coils without material obstruction of radiation therefrom, as specified.

4. In an electric heat unit, the combination of an insulator plate with a suit-able groove in the face thereof, a heating coil disposed in said groove, and a metallic shield plate disposed over said insulator plate with a slot corresponding to the said groove and with a broad rim extending into a supporting flange beyond the said insulator plate, 1said rim having radial slots therein, as speci- 5. In an electric heat unit, the combination of an insulator plate with a groove in the face thereof, a heating coil in said groove, and a metallic shield plate over said insulator plate with slots corresponding to the said groove and extending beyond the insulator plate and serving as a support therefor, as specified.

6. In an electric heat unit, the combination of an insulator plate, heating coils therein, a metallic shield plate carrying said insulator plate, projecting beyond the insulator plate, and a base with a recess to receive said insulator plate and engage the shield nlate, as specified.

y In witness whereof, we have hereunto set our hand and seal in the presence of two witnesses.

MAURICE E. LOUTH. [n s] JESS JACKSON. [Ls] Witnesses:

JAMES C. PAT'roN,

O. R. LIVINGHOUSE. 

